1. Field of the Invention
The invention relates to a method for controlling the drive power distribution in a motor vehicle with hybrid drive.
2. The Prior Art
Hybrid drives, in which an internal combustion engine and at least one electric motor jointly introduce a torque into the drive train of drive machines, are the known. With hybrid drives in which the torque of the internal combustion engine and of the electric motor are jointly used for drive, a different response capacity exists with respect to the change in the torque of the internal combustion engine and of the electric motor. Due to the effect of internal combustion engines, there is always a delay in the conversion of reference moments to actual moments. This delay is particularly attributable to the behavior of the air mass stream in the suction tube, as well as the behavior of the throttle valve and its adjustment. A change in reference moments to corresponding actual moments is implemented almost without delay by an electric motor. In the division of the torques when there is a load change, the delay that occurs in the internal combustion engine must be taken into consideration, for example in order to avoid choking off the engine by a suddenly increased load moment of the electric motor.
A drive system consisting of an internal combustion engine and at least one electric machine, having a regulation is described in German Patent No. DE 197 04 153 C2, in which the control introduces an increase in the torque of the internal combustion engine when a load is applied while the internal combustion engine is in idle, and controls the electric machine in such a manner, until this internal combustion engine intervention becomes effective, to temporarily provide an additional driving torque.
With this regulation method, the electric motor briefly issues an additional torque to a common drive train, only when there is a load change. Generally, the electric motor is not constantly involved in the drive of the vehicle.
A method for controlling the drive power distribution in a motor vehicle with hybrid drive is described in German Patent No. DE 103 37 002 A1, in which a control device controls and regulates the drive power distribution between the internal combustion engine and the electric machine, with regard to the power dynamics and the energy consumption of the vehicle, as well as its pollutant emission and its driving comfort, on the basis of measured and/or calculated values. If a desire for drive power is signaled, existing reference operation values for the operation of the electric machine are changed to reference operating values adapted to the current desire for drive power. For determining the new reference operating values for the electric machine, its future maximal and minimal moments, powers, degrees of effectiveness, and losses are calculated in advance.
With this method, regulation of the division of the torques when there is a load change, taking into consideration the delay that occurs with the internal combustion engine, does not occur
German Patent No. DE 103 33 931 A1 describes a method for regulating an electromechanical, power-branching hybrid drive of a motor vehicle having an internal combustion engine and two electric machines, which are coupled by means of a subsequent gear mechanism. For control, the reference speeds of rotation and the reference torques are calculated for the internal combustion engine and for the two electric machines, in each instance, and the referenced speeds of rotation, in each instance, are compared with the actual speeds of rotation. One or more additional torques are calculated, if there is a deviation in the speeds of rotation, which torques are taken into consideration in the torque control of the internal combustion engine and of the electric motors. In this connection, the speed of rotation regulators of the electric machines are structured as P regulators or PD regulators, and of the internal combustion engine as I regulators, PI regulators, or PID regulators. In this way, the speed of the rotation regulation circuit of the internal combustion engine is provided with an integral part that balances out imprecisions in the torque control of the internal combustion engine.
With this method, only a general balancing out of imprecisions in the torque control of the internal combustion engine takes place. In this case, too, delays occur in a subsequent torque control, by comparing the reference speeds of rotation and actual speeds of rotation, as a basis for the regulation.